A spokesman for the Scottish Government's Transport Scotland agency, which is in charge of the project, said: "Traffic management will come off in December, then return in spring to summer at night for the works."

Work which won't be finished until next year includes work inside the deck and on gantries, external and internal painting, and cable maintenance access cradles.

Neil Greig, of motoring group IAM RoadSmart, said: “Queensferry Crossing users will be rightly frustrated that work continues due to the contractors inability to get the right resources in place.

"They are the experts and they should have been able to predict exactly what was needed and when to try and get more things done before the winter season.

"Transport Scotland should be seeking cast iron guarantees that the new timescale will be adhered to.”

Mr Matheson said: “Our contractor, FCBC, have indicated they have not made the progress with the snagging and finishing works as originally planned.

"The target date for completing this work was September 2018 but they have informed us they require further time.

“FCBC have said they have experienced difficulty in mobilising the resources required to complete the outstanding works on the project.

“But they are confident they will finish all but two areas of the remaining works by December 2018, with work on the remaining two areas to commence in spring 2019.

“Where possible, traffic management will only be implemented during the night, as is standard across the trunk road network.

"In response to feedback from road users about night time traffic management during the summer months, additional processes have been implemented to ensure that traffic volumes are reduced prior to traffic management being installed on the bridge.”

That follows The Scotsman highlighting that lanes were being closed before traffic had eased.

Scottish Conservative transport spokesman Jamie Greene said: “Commuters will see news of more repairs needed, and conclude that the SNP is now playing catch-up after hurrying to open the bridge triumphantly, at the expense of commuters and drivers.

“The fact the bridge is architecturally impressive does not excuse any disruption that will be caused to drivers due to its premature opening.

“There’s never been a back-patting session quite like it from the nationalists after the Queensferry Crossing was officially unveiled last year.

“But now we learn the substantial backlog of snagging works will continue well into the autumn of next year, two years after it originally opened.

“The Queensferry Crossing is a magnificent piece of work, but if journey times have not improved and motorists are facing years of roadworks, you can understand scepticism around this flagship project.”

Edinburgh Western Liberal Democrat MSP Alex Cole-Hamilton said: "I am proud of the crossing which connects my constituency to Fife, but when we first uncovered how far it was from being completed, we were accused of talking Scotland down.

"Now we learn it is going to take an additional 12 months.

"That means the finishing touches will not be in place until almost two years after the bridge was first opened.

"Residents and road users will be fearful that this will mean closures and delays further down the road."

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